Summer squash is almost a “must have” at a farmers’ market stall. Customers love to eat squash in a variety of ways: raw in salads, sautéed with onions, in casseroles and grilled, to name just a few. This means that a market farmer really needs to have summer squash in his/her repertoire. Here at Au Naturel Farm, summer squash is one of those vegetables that we love to hate, but we know our customers will expect it every week, so we grow a lot of it!

All summer squash varieties are member of the cucurbita pepo species, commonly written as c. pepo. Many other types of squash are also in this family, including most of the plants we call pumpkins. This is important information if you intend to save seed, or breed new varieties of summer squash as all will cross-pollinate within the species. There’s nothing like getting a pumpkin when you think you’re planting that yellow summer squash you liked so well that you saved the seed!

Summer squash are tender plants – readily succumbing to frost – and need warm soil and air temperatures to do their best. There are some good ways to extend the season for this vegetable on both ends by providing those warm temperatures when Mother Nature doesn’t. Planting transplants through black plastic mulch and adding row cover can gain you at least 2 weeks over planting seed in bare soil, and add two or three weeks at the end of the season as well. Just remember to remove that row cover when they start to bloom, so pollination can occur. If the squash isn’t pollinated, the baby squash either drops off, or never develops. In the fall, just put the row cover on in late afternoon to protect from the cool fall nights. If you have the room in a high tunnel, you can have the first (and last) squash at your market – capturing the loyalty of many customers for the entire season. Transplants can be put into a high tunnel as much as four or five weeks ahead of outdoor transplanting. However, they take up a lot of room that more profitable plants could use, so make sure it’s a money-making proposition to use that space for squash. In the high tunnels, you may need to hand-pollinate them as well. An easy way to do this is to pick several open male blooms (the ones with stems only, no baby squash behind the bloom), take off all the petals, exposing the anthers, and use them like a paint brush, brushing pollen onto the stigma (center structure, slightly sticky) of the female blooms (the ones WITH a baby squash behind the bloom). It does take time, and as long as we open our high tunnels during the day, we haven’t needed to do this, but during a stretch of inclement weather, with the tunnels closed, it might be necessary.

We plant all our squash as transplants. There are several reasons for this. The first has to do with timing. Since we want a new planting of squash every three weeks, it allows for easier scheduling. Transplants are also easier to plant through plastic or paper mulch than seeds. With a transplant, we get a jump on both insects, and in bare soil, weeds, compared to seeds. The downside is that transplants never grow as robust a root system as seeded plants, so if our reasons for transplanting don’t exist in your situation, you need to consider whether they are worth the trouble.

We grow our squash transplants in jumbo 606’s. Squash hate to have their roots disturbed, and the large cells keep that to a minimum. We use regular planting media incorporating a small amount of the same pelleted chicken manure product that we use in our production and plant 1-2 seeds per cell, depending upon germination percentage on the seed pack. In cool weather, the flats then go on germination mats set to about 80 degrees F in a cool greenhouse. We have plants up in 3-4 days. Squash grow fast, so don’t seed them more than about 3 weeks before transplant date. They’ll probably hold a few days beyond that, but not much more than a week without damaging the transplant. If they get a little yellow, water with some fish emulsion for a quick green-up.

When transplanting, space plants 2-3 feet apart and be sure to handle them gently. At that age, squash have very tender leaves, and any damage you do while transplanting will slow their growth. Along those same lines, if you use row cover, be sure to support it with hoops if you live in a windy area. We have seen row cover abrade squash plants to a bare stem in a heavy wind, and they seldom recover.
Squash, like most vegetables, are mostly water, so good, constant soil moisture is necessary for the best growth. We use drip irrigation on all our crops, so if it doesn’t rain, the crop doesn’t suffer. Drip is also superior to overhead irrigation because it doesn’t wet the leaves, helping to control foliar diseases.

Okay, now for the bad stuff – insects and disease. We have two main insect pests on squash. The first is the cucumber beetle, striped (Acalymma vittatum ) and spotted (Diabrotica undecimpunctata howard, the larva also known as southern root worm). These resemble their cousin, the ladybird beetle, but are a nasty green (maybe it’s not nasty, but I see it that way) with black stripes or spots. We have found them relatively impervious to “soft” controls, but by transplanting rather than seeding, the squash usually outgrows the damage. We have tried Neem products, and Surround, and saw no real difference in cucumber beetle damage. Row covers can help, but need to be removed at flowering for pollination. The second pest, and by far, the worst, is the squash bug, Anasa tristis. The adult is dark gray, about a half-inch long, resembles an elongated stink bug, and smells nasty when squashed. They are “true bugs”, rather than beetles. The female lays eggs on the leaves of squash, both sides, in parallel rows between the veins of the leaf. They are white when first laid, darken to a metallic bronze and are very hard shelled. When they hatch, the nymphs are tiny light gray insects with black legs that resemble their parents. The adults are impervious to “soft” insecticides. The nymphs are less resistant early on, but must be sprayed when small to kill them. Hand picking is moderately effective on small plantings. Be sure to look under any debris under the plant for the insects, and on both sides of the leaf for eggs. When destroying adults, it’s important to remember that crushing them releases a pheromone that attracts other adults, so drowning them is a better solution. Eggs must be destroyed – they will hatch on the ground. Alison cannot squash them between her fingers, she has to use fingernails or drop them into a can of soapy water and dispose of them later. Adults can also fly up to a half-mile – we have had them fly in on storm fronts. And, although everything you read says they have only one generation, here in southern Kentucky, we see egg-laying from April (in the high tunnels) until frost and are sure we have at least two generations. So, what do we do? We succession plant. By the time a planting has a problem, we have a fresh planting coming along, and just turn the old under, bugs, eggs and all. Great organic matter! We tried Surround on summer squash, and gained about a week of harvesting, but the clay residue was difficult to wash off, and made our squash look “sprayed” – a turn off for our market.

The squash family has a variety of foliar diseases. Our worst is powdery mildew. We seldom see it anymore because we use drip irrigation, keeping moisture off the leaves, and we succession plant. Squash, especially yellow summer, can also have viral diseases such as cucumber mosaic virus and watermelon mosaic virus which cause green color mottling. To combat them, use a variety that has a precocious yellow gene that “masks” the green color – they’re still infected, but look okay.

Speaking of varieties, it almost goes without saying, but we’ll say it anyway – grow what your market wants! We sell very little zucchini, no patty pan, and lots of yellow straight-neck. So, we can’t say we have “favorite varieties” of patty pan or zucchini. However, for yellow squash, we LOVE Zephyr, a hybrid available from Johnny’s. It’s uniquely colored and great tasting – our customers rave about it. For our standard yellow, we really like Early Prolific Straightneck, an open-pollinated variety. It seems to be a lot more resistant to squash bug, and we could, if we wanted to take the trouble, save the seed. While doing research for this article, we became aware of how many transgenic (GMO) varieties of summer squash are available. Most are for disease resistance or color masking. So, if being non-GMO is important for you, read variety descriptions carefully when dealing with seedsmen who have not signed the Safe Seed Pledge. And, most of the transgenic varieties seemed to have II or III as part of their name as in Precious II.

Last, but not least, harvest and handling. Harvest summer squash small and often. Very few customers will buy a three-pound zucchini! They taste better when they are small. For zucchini, for us, the very largest we harvest is about 8 inches, for yellow squash, about 6 inches. We harvest every day during the hot summer months and the day before market, we harvest everything, even the smallest, (usually gives us Sunday off from harvesting!). We time that harvest for early morning, before there is much field heat in the squash. Handle the fruits very gently, even wearing gloves if you have long fingernails (yeah, I know, farmers with long fingernails!). Every scratch or bruise will show up as a brown spot after a day or two. Then, we gently wipe off any dust (here’s where Surround caused us problems) and place them in a container to refrigerate until market.

That’s it! Have good varieties, earlier than anyone else, harvest well and often, handle the harvest gently, and make your customers happy with terrific summer squash all season.

Paul and Alison Wiediger have 2.5 acres of vegetable production, 8500 square feet of high tunnels and a greenhouse operation on their 84 acre diversified farm in Edmonson County, Kentucky. Their book about growing in high tunnels, Walking to Spring, is available for $15 plus $4 shipping from GFM, PO Box 3747, Lawrence, KS 66046; 800-307-8949; www.growingformarket.com.